Twitter said Wednesday it fixed a security vulnerability in its TweetDeck application and turned the service back on following a breach that affected users for a few hours.

Earlier, people who were logged in to the service started receiving random pop-up messages and unknowingly retweeting messages with random code script. The problems appeared to persist even after TweetDeck’s account said the security issue had been resolved, advising users to log out of the service for the fix to take effect. The account sent a follow-up tweet saying Twitter temporarily took TweetDeck down. The service was disabled for about an hour.

Twitter declined to comment. But one or more users appear to have exploited a problem with “cross-site scripting,” or XSS, on TweetDeck. Cross-site scripting is a common vulnerability for websites.

In this case, the vulnerability allowed TweetDeck to misinterpret text as programming commands that prompted other actions, said Trey Ford, a security strategist at Rapid7. He said one user tweeted a message with JavaScript commands that caused anyone exposed to the tweet in TweetDeck to automatically retweet it. Within several hours, that tweet had been retweeted more than 84,000 times. It appears there were other problematic tweets containing code that caused other forced actions, such as popup windows.

Logging out of TweetDeck would terminate the bugs’ effect, Ford said. Twitter advised the same.

For the most part, this breach was harmless to users beyond the disruption. Ford said while other attacks have threatened password security, that does not appear to be the case with the breach on TweetDeck. At worst, it annoyed Twitter’s power users for a few hours.

An infamous version of this attack first took place in 2005 when a cross-scripting site worm altered over one million personal user profiles on MySpace.

TweetDeck, which was purchased by Twitter in 2011, is a popular platform used primarily by power users such as news organizations. It allows people to view and manage tweets through multiple feeds on one screen.

There are multiple ways people can access TweetDeck — a downloadable app for Windows or Mac, via a browser app for Chrome.